Add IP address scope to existing scope

I have one subnet for our growing company (192.168.5.0) that has been exhausted. I'm now getting IP address conflicts throughout the network. I would like to keep this subnet intact but expand it to:

192.168.0.0 - 192.168.255.255

How easy is this done. Can I simply right-click the 192.168.5.0 existing scope and change it or is there more to it?

DHCP Scope
jness00Asked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

netcmhCommented:
0
Fred MarshallPrincipalCommented:
You're asking about DHCP.  And, this is a fine place to start.
First, you might ask if there are static IP addresses (like your internet gateway, servers, printers, etc.) that are currently in use.  If so, you don't want your DHCP scope to overlap.

Starting with a subnet of 255.255.255.0 or /24, it seems a bit extreme to go from that (with 254 usable addresses) to one with 65532 usable addresses.  That's what you'd be getting with xxx.xxx.0.0 to xxx.xxx.255.xxx.

Now, that's all fine if all we're talking about is the subnet range.  But the question is focused on DHCP settings.
You should not be getting IP address conflicts if using DHCP in the first place.  So there must be static addresses that overlap with the DHCP address range.  That's not good or recommended practice.

So:
Pick the size of the range that you want.  In your case, with addresses in 192.168.5.0/24 I'd guess you have static addresses in there somewhere - above .249 perhaps like .250-.254??  And 254 usable addresses is too small it appears so what's wrong with 510 or 1022 addresses?    In some sense it doesn't matter but in terms of how you manage it and plan for further expansion, it does.  I would add more than enough and stop there.  Thus 510 or 1022 total.

If you change to 192.168.4.0/23 or 255.255.254.0 then you could set up DHCP from:
192.168.4.5 (leaving 4 spares at the bottom of the range) to 192.168.4.255 or 192.168.5.0 or ..... leaving the current addresses in 192.168.5.1 and beyond - which would preserve the static addresses (almost - see below).

Here is what I generally recommend:

1) Change the subnet of the internet gateway (and other critical routers) to match the new subnet.  
With reasonable luck, things will continue to work as long as the ranges overlap from "old" to "new" because the old IP addresses will still be on the new subnet.

2) Change the DHCP scope.

3) Cancel all the DHCP leases, forcing them to be redone.

4) Change the settings in all the statically-addressed devices to have the new subnet mask.  If the plan is done reasonably there would be no reason to change their IP addresses, just the mask.

Many things won't be affected by a mask mismatch of overlapping subnets so this might not be noticed at all in the transition.  I would still get it all done in the shortest time possible and get it done completely leaving no "old" subnet masks.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Windows Networking

From novice to tech pro — start learning today.